From the Document: "Worker risk of occupational exposure to SARS-CoV-2, [severe acute respiratory syndrome coronavirus 2] the virus that causes COVID-19 [coronavirus disease], during an outbreak may depend in part on the industry type and need for contact within 6 feet of people known to have, or suspected of having, COVID-19. OSHA [U.S. Occupational Safety and Health Administration] has divided job tasks into four risk exposure levels, as shown below. Most American workers will likely fall in the lower exposure risk (caution) or medium exposure risk levels."
OSHA 3993-03 2020; Occupational Safety and Health Administration 3993-03 2020
U.S. Occupational Safety and Health Administration: https://www.osha.gov/